选择合适的单词填空。
am is are can can't Would don't
某同学用如图1所示装置测量重力加速度g,所用交流电频率为50Hz.在所选纸带上取某点为0号计数点,每两个相邻计数点间有2个点未画出,所有测量数据及其标记符号如图2所示